Introduction: Machining 101: Lamp Training, Lamp Base

I have been one of the lead machine shop teaching assistants at the Emerson Machine Shop at Cornell University for a couple of years now. The Emerson Shop is open to anyone who wants to learn and is also integrated into the core curriculum of mechanical engineers at Cornell. Our sophomore Mech E.'s undergo shop training as part of the core curriculum (MAE 2250: Mechanical Synthesis) to learn to use the tools available to them (mills, lathes, saws).

Throughout the course, they work to design and manufacture all of the parts of a water pump (or air motor). However, rarely do I ever see them return to the shop after the conclusion of the course. A large reason for this is that once they leave the shop, they forget how to use the tools and become nervous about machining.

It takes a lot of time and physical practice to become comfortable (and good) at machining (or at anything at all). I am writing this tutorial is to serve as a refresher on the basic steps and safety precautions to take when operating a mill and lathe. This lamp training is designed to introduce the fundamental capabilities of shop tools, which in reality can lead to the creation of anything you can imagine.

This Lamp Training Instructable is broken up into two components: Conquering the Mill and Conquering the Lathe.

Step 1: Gather Your Tools and Materials

The first thing I do whenever I machine is plan, plan, plan. I like being able to hop on a machine and maneuver through the steps of making a part. I'll have all the steps and tools I need planned out and ready for use. This habit resulted from having an enormous amount of work to do in a very limited amount of time (and in between classes).

The lamp that this Instructable will teach you to make is made up of two machined parts: the lamp base and the lamp stem, which will be made on the mill and lathe, respectively. The stock materials, tools, and accessories required for the lamp base are listed below here.

Materials for the lamp base:

  • Stock: 5" x 5" x 0.5" aluminum
  • Tools:
    • parallels
    • end mill, at least 0.5" length (with corresponding collet)
    • edge-finder (or wiggler)
    • center drill + 1/4" diameter drill bit + 3/8" diameter drill bit + 29/64" diameter drill bit
    • counter sink + stopper
    • 1/2-20" tap + tap handle
    • cutting fluid
    • deadblow hammer
    • file (not shown in image)

Lamp accessories

  • (threaded insert)
  • lamp + light bulb

Step 2: Conquering the Mill - Set Up Your Stock

We will focus on making the lamp base on a mill.

When ordering aluminum stock, you should always try to get your dimensions as close as possible to what you want. I usually order my stock (and most other items) from McMaster-Carr. In this Instructable, I am using stock left-over from another project. The original material came in a 2-ft length of aluminum, and I used a band saw to cut this piece off the end. As shown in the image, the material has two smooth finish edges and two rough edges. The smooth edges are what you will use to help keep your part square as you machine it.

Tip: Prior to setting up your mill, you want to make sure to clean off your vice and get rid of any metal chips. You can do this using a brush, a shop towel, or compressed air. This will ensure that you secure your part properly into your vice.

To set-up your mill, place your two parallels on the inside faces of the vice and place your stock aluminum on top. Tighten your vice and using a dead-blow hammer, tap the part and tighten the vice further to make sure that the part is sitting flat and securely in the vice.

Tip: Try moving your parallels. If they don't move, you can be confident that your part is secure. If the slip and slides, you're not quite there yet! Try to loosen your vice and repeat the process. Make sure that your parallels are wiped clean of any chips! Chips will prevent your part/parallel from sitting flush inside the vice.

Step 3: Conquering the Mill - Cutting Your Stock

The mill that I am using requires that the collet be changed manually. It has been pre-setup with a Jacobs chuck for easier and quicker tool changes. In this step, you will first face-off one edge, flip the part around, and cut your part down to size.

Facing your first edge.

  1. Load the end mill into the chuck (tighten using the key).
  2. Lower the quill so that the end mill passes the lower face of the part. Raise the Z-axis if your tool doesn't reach your part.
  3. Turn on the spindle (speed = 750 RPM, high gear).
  4. Slowly move the end mill in the x-axis just until it just touches the part. This is called a "touch cut."
  5. Now that your tool is touching the part, move your way down the part in the y-axis. This is a single pass.
  6. Keep making passes by move your tool into the part, until you have full contact between the part and the tool (the entire face will looks like it has a machined finish).
  7. Turn off your mill and retract your spindle.
  8. To clean off your part, angle the file away from you (with the handle towards you) and push down on the edges. This will take off any sharpness and prevent you from cutting yourself.

Safety Tip: NEVER start the spindle with your tool touching your part.

Facing your second edge.

  1. Loosen your vice and flip your part so that the other rough edge is ready for machining. Secure it the same way as in Step 2.
  2. Repeat steps 2 thru 6, above.
  3. Once you have a full contact pass, you can zero your x-axis on your DRO read-out.
  4. Clean your part as in step 8 above. You want to do this before any time you measure your stock because burrs can through off your measurements.
  5. Measure the length of your stock with calipers. Take the difference between your stock length and desired length. This will be the amount of material you need to take off on this edge. (In this case, I want my lamp base to be 5 inches, but it is currently 5.68 inches so I will be removing 0.68 inches).
  6. Making 0.020" passes, machine your part until your DRO reads the length determined in step 5.
  7. Repeat step 8, above.

Step 4: Conquering the Mill - Finding Your Zero

In order to navigate around your part, you will need to set a zero reference point. This is the point that any feature (ie. holes) will be referenced .

Zeroing your x-axis.

  1. Load your edge-finder (also called wiggler) into your chuck.
  2. Lower your quill so that the bottom loose section of the edge-finder align with the right hand edge of your part.
  3. Offset the bottom of your edge-finder.
  4. Turn on your spindle (speed = 750 RPM, high gear).
  5. Slowly move your edge-finder in the x-axis until you can visually see the bottom section of the finder align with the top shank.
  6. Zero your x-axis read-out on your DRO.
  7. Since the diameter of my edge-finder has a 0.20" diameter head, you will need to offset the spindle by 0.10" to account for this diameter.

Zeroing your y-axis.

  1. Repeat steps 1 thru 7, but for the bottom edge of your part instead.

Step 5: Conquering the Mill - Drilling Your Hole

Once you have found your zero (in this case, the bottom right hand corner of the part), you can now set-up to drill out and tap the hole for your lamp stem.

Drilling your lamp base hole.

  1. Load your center drill into your chuck.
  2. Maneuver the spindle so that it reads X 2.50" and Y 2.50" on your DRO. This is the center of your part!
  3. Turn on your spindle (speed = 750 RPM, high gear).
  4. Lower your spindle so the center drill creates a pilot hole.
  5. Turn off your spindle and change your tool to the 0.25" drill bit.
  6. Turn on your spindle (speed = 750 RPM, high gear).
  7. Peck drill your hole until the drill bit is completely through the part.
  8. Repeat steps 5 thru 7, with the 0.375" drill bit.
  9. Repeat steps 5 thru 7, with the 0.50" drill bit.
  10. Load your chamfer tool.
  11. Lower the tool until it touches the top surface of the hole. Create a slight chamfer on the lip of the hole.

Safety Tip: Peck drilling is when you drill into your part and lift your tool at intervals in order to break chips that form. This prevents long chips from forming and flinging around (particularly at your face).

Re-positioning your part.

A stopper is sometimes used to help you mark the location of your part with respect to the vice. This allows you to re-position your part without having to re-find your zero.

  1. Place your stopper up against your part on the lip of the vice and tighten it down.
  2. Loosen your vice and flip your part around so that the not-chamfered edge of the hole is facing upward. Make sure that the same edge is still touching the stopper.
  3. Tighten your part in your vice.
  4. Repeat step 11, above.

Step 6: Conquering the Mill - Tapping Your Hole

The final step to completing your lamp base is to tap the hole that you made in step 5. This is the hole that hold your lamp stem.

Tapping your hole.

  1. Take your 1/2-20 tap and secure it into your tap handle.
  2. Load your tap guide into the chuck. This spring-loaded tap guide will help you keep your tap straight.
  3. Place your tap (+handle) over your hole, and lower your quill so that the tap guide is pressed into the tap.
  4. Put some cutting fluid on your tap. This will make it easier for the tapping process.
  5. Turn your tap handle in clockwise turns. Every 2 or 3 turns, you should reverse the tap to break the chips formed. Continue this pattern until the tap makes its way through the hole.

You are have now completed your lamp base!